1. Field of the Invention
This invention relates generally to electronic assemblies, and, more particularly, to thermal management of electronic assemblies.
2. Description of Related Art
Many modern electronic systems are constructed from circuit board assemblies. As is known, a circuit board assembly includes electronic components that mount to an insulative substrate. Wires or traces are placed on different layers of the substrate to electrically interconnect the components. A circuit board assembly generally includes one or more connectors for attaching the assembly to other parts of an electronic system, and may include multiple tiers of circuit boards connected together.
Circuit board assemblies are typically provided in standard sizes and shapes. Standardization allows the assemblies to plug into a standardized chassis, or “card cages.” A typical card cage has a front face with an opening for receiving circuit board assemblies and a backplane located toward the rear of the card cage. The backplane has connectors for making blind mate connections with the circuit board assemblies. Circuit board assemblies are generally inserted into the opening of the card cage at fixed locations, called “slots.” One or more connectors on each circuit board assembly mates with one or more respective connectors on the backplane. Conductive pathways within the backplane allow transmission of electrical signals between different circuit board assemblies.
A card cage can generally accommodate different numbers and types of electronic assemblies. Numerous instances of any one type of assembly may be provided together in a card cage. In addition, different types of assemblies can be provided within a card cage.
Within electronic systems, a card cage is often bolted to a frame, generally called a “rack.” The rack may hold multiple card cages, as well as other equipment. Racks for holding electronic equipment are generally provided in standard sizes, such as the common 19 inch (48.3 cm) rack.
As is known, electronic assemblies require adequate cooling to function properly. As electronic components become smaller, packaging density tends to increase. Not only are more components packed into smaller spaces, but also more power is often consumed in smaller spaces. This increased “power density” creates new challenges for system designers.
As is known, liquid is generally capable of conducting away heat from electronic components more effectively than air. Consequently, system designers are increasingly turning to liquid cooling techniques to address the thermal needs of assemblies having high power density.
System designers often wish to continue to use the same standard sized assemblies and racks as have been used in the past. They also wish to have the same flexibility as before, in terms of being able to vary the number of assemblies of any one type and the different types of assemblies installed in a card cage.
Therefore, it would be desirable for a liquid cooling system to be suitable for use with standard sized circuit board assemblies, card cages, and racks. It would also be desirable to be able to vary the amount of liquid cooling capacity according to the number and types of circuit board assemblies used.